By philosophy, praxis, and penetration, I refer to pariyātti, paṭipatti, and paṭivedha, in that order.
Pariyātti is studying the Ḍhammā. It is learning the Ḍhammā. It is gaining knowledge of the Ḍhammā. It is the base. Relying on it, paṭipatti arises.
Paṭipatti is practicing the Ḍhammā. It is exercising the Ḍhammā. It is gaining experience in the Ḍhammā. It is the middle. Relying on it, paṭivedha arises.
Paṭivedha is realizing the Ḍhammā. It is understanding the Ḍhammā. It is gaining the fruit of the Ḍhammā. It is the top. Relying on it, one achieves nibbāna.